Spring-loaded bladed hand tool

ABSTRACT

A force reducing bladed hand tool designed to allow the tool&#39;s blade to rotate so that the working edge of the blade is continuously aligned for optimal cutting or scraping with each arm movement. In the first embodiment, the hand tool is a knife with a hollow handle with a longitudinally aligned tension spring located therein. Mounted on the distal end of the handle is a connector with a downward extending spline attached thereto. Pivotally attached to the spline is an elongated blade with a cutting edge. The proximal end of the blade is attached to a coupler which connects at an opposite end to the spring bias the blade inward through the connector and towards the handle. During assembly, a pivot pin is extended through the bore in the spline and a complimentary bore formed on the blade. The pivot pin and the lower slot on the connector enables the distal end of the blade to pivot upward when excessive pressure is exerted on the handle by the user&#39;s hand.

This is a utility patent application which claims benefit of U.S. Provisional Application No. 61/132,930, filed on Jun. 23, 2008.

COPYRIGHT NOTICE

Notice is hereby given that the following patent document contains original material which is subject to copyright protection. The copyright owner has no objection to the facsimile or digital download reproduction of all or part of the patent document, but otherwise reserves all copyrights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to hand tools with cutting or scraping blades, and more particularly to such tools that require the exertion or application of continuous force against the tool's handle to cut through or pry apart an object or surface.

2. Description of the Related Art

In some occupations, such as insulation installers, workers are required to cut through material, such as fiberglass batting, using an elongated hand knife. The worker is often required to cut and trim fiberglass batting with the knife. Typically, the worker holds the knife with a locked wrist and then uses a vertically aligned, continuous arm stroke to force the blade through the batting.

The batting is often cut to size after being installed between studs or rafters. The tip of the blade penetrates the batting and is hidden from view. As the blade is moved in a continuous stroke, the tip of the blade contacts the inside surface of the adjacent wall or ceiling. As a result, the amount of force exerted by the hand on the knife's handle varies during the arm stroke. For a professional installation installer, who installs and cuts batting on full time basis, the variation of force on the wrist can lead to wrist injuries. Also, because the tip of the knife is dragged across the inside surface of the wall or ceiling, it quickly becomes dull which reduces the lifespan of the blade.

Carpeting is often glued down over a cement subfloor. When replacing carpeting, the old carpet and glue must be scraped off the subfloor which is very difficult and labor intensive. In the prior art, scraping tools with an elongated pole and a rigid scraping blade have been used. During use, the edge of the scraping blade is placed on the subfloor and then pushed and pulled over the subfloor trying to dislodge the old glue and carpeting. Occasionally, the user holds the scraping blade against a free edge of the carpeting and uses the scraping blade as a wedge to pull the section of the carpeting upward and away from the subfloor. During the process, it is important that the edge of the blade be maintained at a proper angle so that the blade can easily slide back and forth over the subfloor and still act as a wedge.

What is needed is a spring loaded bladed hand tool with a cutting or scraping blade that automatically pivots on the end of the handle during use to maintain the blade at its optimal cutting or scraping angle during use.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved bladed hand tool with an elongated handle and a pivotally attached blade.

It is an object of the present invention to provide such a hand tool in which the blade automatically pivots on the end of the handle during use so that the blade is constantly positioned at an optimal cutting or scraping angle.

These and other objects are met by the hand tool disclosed herein designed to allow the tool's blade to pivot when excessive downward force is exerted on the handle by the user's hand. The tool includes a hollow handle with a longitudinally aligned spring located therein. The spring includes an optional index tab that extends through a slot formed on the surface of the handle to visually inform the user the amount of tension exerted by the spring. Attached to the distal end of the spring is a tension rod that connects to the proximal end of the blade.

In the first embodiment, the tool is a cutting knife with an elongated cutting blade mounted on the distal end of a handle. The handle includes a hollow connector with a lower slot opening formed therein. Attached or formed on the connector is a rigid, downward extending spline with a transversely aligned bore formed therein. Extending from the connector is a longitudinally aligned blade with a lower cutting edge. The proximal end of the blade is attached to the coupler connected at one end to the spring, which bias the blade inward through the connector and towards the handle. Connected to the lower end of the spline is a pivot pin that extends into a complimentary bore formed on the proximal end of the blade. An optional blade holder may be aligned over the top edge of the blade which is used a protective contact surface for the user's fingers and as a blade stabilizer.

During use, when excessive pressure is exerted on the distal end of the blade, the distal end of the blade is able to pivot upward and around the pivot pin. The proximal end of the blade rotates downward and extends through the slot formed on the hollow connector. As the proximal end is rotated downward, a biasing force is exerted on the proximal end of the blade which returns the blade to a longitudinal aligned position when the force exerted on the distal end of the blade is removed.

In a second embodiment, the tool is a scraping tool with a scraping blade pivotally attached to an elongated handle. Located inside the handle is a tension adjustable spring that enables the user to adjust the about of tension required for the scraping blade to pivot on the end of the handle.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of the spring loaded, bladed hand tool in the shape of a hand knife.

FIG. 2 is a bottom plan of the force reducing hand knife shown in FIG. 1.

FIG. 3 is a partial side elevational view of the connector used with the hand knife embodiment shown in FIGS. 1 and 2.

FIG. 4 is a proximal end of the blade being rotated in the connector

FIG. 5 is a partial side elevational view of the knife showing the connector and blade.

FIG. 6 is a front elevation view of the connector taken along line 6-6 in FIG. 5.

FIG. 7 is a rear elevational view of the connector taken along line 7-7 in FIG. 5.

FIG. 8 is a side elevational view of the tension link.

FIG. 9 is a top plan view of the tension link.

FIG. 10 is a side elevational view of a flooring or roof shingle removing tool.

FIG. 11 is a top plan view of the flooring or roof shingle removing tool.

FIG. 12 is a partial side elevational view of the distal end of the elongated handle showing the blade rod aligned longitudinally with the distal end of the handle.

FIG. 13 is a partial side elevational view of the distal end of the elongated handle showing the blade rod aligned diagonally on the distal end of the handle.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to the accompanying FIGS. 1-13, there is shown a spring-loaded bladed hand tool 5 that includes a pivotally attached blade designed to move to maintain proper position for cutting or prying and to reduce pressure exerted on the user's arms and shoulders. In the first embodiment, the hand tool 5 is a knife 10 designed to allow the knife's blade 50 to rotate and reduce excessive downward pressure exerted on the handle 12 by the user's hand thereby reducing injuries. The knife 10 includes a hollow handle 12 with a longitudinally aligned coil spring 20 located therein. The coil spring 20 includes an optional index tab 26 (shown in FIG. 2) that extends through a slot 16 formed on the surface of the handle 12 to visually inform the user the amount of tension exerted by the coil spring 20. Attached to the distal end 22 of the coil spring 20 is a tension link 40 that extends between the proximal end of the blade 50 and the coil spring 20.

Mounted on the distal end of handle 12 is a hollow connector 30 with a lower slot opening 34 formed therein. Attached or formed on the connector 30 is a rigid, downward extending spline 36 with a transversely aligned bore 38 formed therein. Extending from the connector 30 is a longitudinally aligned blade 50 with a lower cutting edge 52. The proximal end of the blade 50 is attached to the tension link 40 connected at one end to the spring 20 which biases the blade 50 inward through the connector 30 and into the handle 12. A first pivot pin 48 is used to pivotally connect the rod 40 to the proximal end of the blade 50. Connected to the lower end of the spline 36 is a pivot pin 60 that extends into a complimentary bore formed on the proximal end of the spline 36 and blade 50. An optional blade holder 70 may be longitudinally aligned over the top edge of the blade 50 and fits under the connector 30 which is used a protective contact surface for the user's fingers and as a blade stabilizer.

In the first embodiment, the handle 12 is designed to fit into the user's palm so that the user may cut with the knife 10 by swinging the arm downward in one continuous motion.

During use, when excessive pressure is exerted on the distal end of the blade 50, the distal end of the blade 50 is able to pivot upward and around the pivot pin 60 as shown in FIG. 4. The proximal end of the blade 50 rotates downward and extends through the slot 34 (see FIG. 3) formed on the hollow connector 30. As the proximal end is rotated downward, a biasing force is exerted on the proximal end of the blade 50 by the spring 20 which returns the blade 50 to a longitudinal aligned position when the force exerted on the distal end of the blade 50 is removed.

Attached to the proximal end of the handle is a rotating cap 80. Attached to the cap 80 is a threaded rod 82 that extends longitudinally inside the handle and connects to a threaded bore or nut 85 attached to the proximal lend of the coil spring 50. By rotating the cap 80 on the handle, the user may change the tension force exerted by the coil spring 20 on the blade 50.

In a second embodiment, the hand tool 5 is a flooring or shingle removal tool 100 designed to allow a scraper blade 130 to rotate over the end of the tool's elongated handle 110 so that momentum force created by the user is transferred to the tip of the scraper blade 130 thereby forcing it against dried glue 97 or nails that hold the carpet 98 or shingles on a subfloor 99 or a roof, respectively. The tool 100 includes a hollow, elongated handle 110 designed to be held by two hands. Extending from and pivotally attached to the handle is a scarper blade 130. As shown in FIG. 11, located inside the handle 110 is a longitudinally aligned tension spring 114. In the preferred embodiment, the tension spring 114 is connected to a threaded rod 116 that connects to a rotating end cap 118. The rod 116 connects to a threaded nut or receiver attached to the proximal end of the spring. By rotating the cap 118, the rod 116 may be extended or retracted in the elongated handle 110 thereby adjust the relative tension of the spring 114 inside the handle 110.

The scraper blade 130 includes a flat blade portion 132 with a perpendicularly aligned rod 134 extending from its upper edge. The rod 134 is slightly smaller than the handle 110 so that rod 134 may fit into the handle 110 during assembly. The flat blade portion 132 is relatively thin with a top and bottom flange surfaces 131, 133, that are substantially parallel and specially designed to be inserted into a gap located between to surfaces.

As shown in FIGS. 12 and 13, the proximal end of the rod 134 is pivotally attached to the distal end 111 of the handle 110. The distal end of the handle 110 is open and includes a lower slot opening 112 that enables the upper end of the rod 134 to rotate through. A first pin 116 extends transversely through the handle 110 and the proximal end of the rod 134 to pivotally connect the proximal end of the rod 134 to the distal end of the handle 110.

Pivotally attached to the section of the rod 134 that extends into the handle 110 is at least one rigid link member 140. A second pin 142 pivotally connects the linking member 140 to the section of the rod 134 located inside the first pin 116. A third pin 152 connects the proximal end of the linking member 140 to an intermediated leaf spring connector 150. The intermediate leaf spring connector 150 is able to pivot on the proximal end of the linking member 140 The spring connector 150 includes a downward extending hook member 154 that engages a short flexible strap 160 that extends into the handle 110. The opposite, proximal end of the strap 160 is connected to the distal end of the coil spring 114. A nut 170 is attached to the upper end of the coil spring 114 that connects to the distal end of the threaded rod 116. By rotating the cap 118 clockwise or counter-clockwise, the tension exerted by the coil spring 145 on the blade's rod 134 may be adjusted for different tasks.

As shown in FIGS. 12 and 13, during normal use, the coil spring 114 exerts a tension force f(1) on the leaf spring 160 that pulls the rod member 134 on the scraper blade 130 into the handle 110. When the edge of the scraper blade 130 is placed around a surface and a downward force f(2) is exerted on the handle 130, (shown in FIGS. 10 and 13) the proximal end of the blade's rod 134 pivots and is forced outward through the slot opening. Because the handle 110 of the hand tool 100 is diagonally aligned on the floor or roof, (see FIG. 10), the distal edge or the scraper blade 130 is forced outward against glue or nails and thereby dislodging the carpet 98 or shingle from the subflooring 99 or roof.

In compliance with the statute, the invention described herein has been described in language more or less specific as to structural features. It should be understood however, that the invention is not limited to the specific features shown, since the means and construction shown is comprised only of the preferred embodiments for putting the invention into effect. The invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the amended claims, appropriately interpreted in accordance with the doctrine of equivalents. 

1. A spring loaded bladed hand tool, comprising: a. a hollow handle includes an opened distal end and a proximal end; b. a rotating end cap attached to said proximal end of said handle; c. a coil spring longitudinally aligned inside said handle; d. a blade pivotally a connected to said distal end of said handle, said blade includes a proximal end and section that partially extends into said handle and rotates downward from said handle when sufficient force is exerted on the distal end of said blade; e. means for coupling said section of said blade that extends into said handle to aid coil spring; and, f. means for adjusting the tension of said coil spring connector attached to an over said distal end opening of said handle.
 2. The spring loaded bladed hand tool, as recited in claim 1, wherein said blade is an elongated blade with a lower cutting edge.
 3. The spring loaded bladed hand took, as recited in claim 1, wherein said blade includes two flat surfaces perpendicularly aligned and mounted on a rod that fits into said distal end of said handle. 